1. Field of the Invention
The present invention relates to a projection type display device and a projection control method.
2. Description of the Related Art
Inside a vehicle such as an automobile, a train, a heavy machine, an aircraft, or a ship, a vehicle head-up display (HUD) that projects, using a combiner disposed in a front windshield or in the vicinity of the front windshield as a screen, light to the screen to display an image is known (see JP1995-257228A (JP-H07-257228A) and JP2006-327310A). In a case where such an HUD is used, a user (for example, a driver) who is present inside the vehicle may visually recognize an image based on projection light projected from the HUD as a real image on the screen or as a virtual image in front of the screen.
JP1995-257228A (JP-H07-257228A) discloses a vehicle HUD that detects a line of sight of a driver and projects light based on image information onto a projection surface only in a case where a sight line direction is present on a path in front of a vehicle.
JP2006-327310A discloses an HUD that controls a spatial frequency of an image based on projection light so as not to cause focus adjustment reaction of a driver.